This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Structural studies on several ligand complexes of dihydroorotase, 5-(carboxyamino)- imidazole ribonucleotide mutase, and N5-carboxyaminoimidazole ribonucleotide synthetase, and spectrin are ongoing. We are carrying out high-throughput screening and in-silico screening on first three enzymes in this list, to develop new chemical compound inhibitor scaffolds and thus, new classes of broad spectrum antibiotics. Initially, we are targeting dihydroorotase from B. anthracis, P. falciparem, M. tuberculosis, and S. aureus. The study of spectrin complexes is linked to understanding the mechanism of apotosis.